Diaphragm



Feb. 9, 1932.

vcr/115552 W. L.. TYRRELL DIAPHRAGM Filed June 14, 1928 INVENTOR.

0mm/L JW@ BY 9, om la, ATTORNEY.

Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE WILBUR lL. TYRRELL, OF -AUDUBON, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS,

To RADIO CORPORATION OF AMERICA, DELAWARE or NRW YORK, 1v. Y., A CORPORATION OF DIAPHRAGM Application led .Tune 14,

My invention relates to a diaphragm for acoustical purposes.

In accordance with myinvention, a member or Vsection of diaphragm-forming material is so corrugated lthat the contour of said member or section is substantially unaltered with resultant Y increase in mechanica-l strength and improvement in acoustic qualities.

Further in accordance with my invention, a member orl section o f diaphragm-forming materialis corrugated to a degree usually numericallyV exceeding 100 corrugations per square inch VJfor the useful purpose aforesaid.

Further in accordance with my invention, either before, while, or after a member is brought to diaphragm-forming configuration, a surface or face thereof is so corrugated that the contour of said member is substantially unaltered. y

More particularly in accordance with my invention, the aforesaid oorrugating operation is performed simultaneously with a diaphragm-forming operation, such, for example, as adie shaping operation including, as a feature, the interposition of a sheet of fabricbetween one die and a face of the diaphragm-'forming member'.`

My invention resides rin the novel diaphragm and in the novel method of producing'the same as hereinafter described and claimed. y y

Foran illustration of some of the vforms my Vdiaphragm may take and for an understanding of my method, reference is to be had to the accompanying drawings in which Figure'l is a plan view of a diaphragm constructed in accordance with my invention.

Fig. 2 is a vertical sectional view of the diaphragm shown in Fig. l.` Fig. 3 is a plan viewof another form of diaphragmpconstructed in accordance with my invention.

Fig. 4 isa vertical sectional view of the diaphragm shown in Fig. 3.

Fig. 5 is a side'elevational view of the `diaphragm shown in Figs. 3 and 4f land having an actuating memberprojecting therefrom and secured thereto.

Fig. 6 isan enlarged sectional view show- 1928. Serial No. 285,462.

ing a diaphragm and the corrugating structures on opposite sides thereof.

Fig. 7 is a vertical sectional view of a die structure and associated corrugation-forming members.

In each of Figs. 2, 4, 5 and 7 the diaphragm is shown as having a thickness much greater than the actual thickness of the material from which the diaphragm is usually constructed. Hence, said Figs. 2, fl, 5 and 7 do not represent the corrugations with entire accuracy. In Fig. 6, the various dimensions are more nearly proportionately correct and, therefore, this View substantially correctly illustrates one form of diaphragm after it has been corrugated in accordance with my invention.

Referring to Figs. l and 2, there is illustrated a diaphragm D of circular configuration and comprising, when looking at one face thereof, a centrally disposed depression l and a plurality of channels 2 concentrically disposed with respect to the diaphragm center. In the example illustrated, diaphragm D comprises two of the aforesaid channels 2 while outwardly of the outermost channel 2 said diaphragm D comprises a circular corrugated section 3 bordered by a plane section 4.

A diaphragm of the character described above is usually, although not necessarily, formed by a die shaping Opera-tion, the wall structure of the depression l and channels 2 forming major corrugations concentrically disposed with respect to the diaphragm center. The alternate ridges and depressions comprised in the diaphragm section '3 also constitute major corrugations which extend tangentially with respect to a circle having the center of the diaphragm D as its center.

The aforesaid major corrugations in the diaphragm D improve its acoustic properties and their utilization is desirable when the diaphragm is comprised in the sound box of a talking machine, phonograph, or the like.

In accordance with my invention, to further enhance or improve the acoustic performance of the diaphragm D, it is provided on one or both faces thereof, as illustrated, with al plurality of minor indentations. and

projections such as corrugations or the like that are minor in size in contradistinction to the aforesaid major corrugations.

Referring to Figs. 3 and 4, there is illustrated another diaphragm D1 constructed in accordance with my invention. This diaphragmoomprisesa. substantially plane outer section 5 surrounding an inner corrugated section 6, the corrugations of the section 6 extending tangentially with respect to a circle having its center at thecenter of the diaphragm D1. The corrugated section 6 merges into a conical section 7, angularly related with respect to the plane of the section 5. Gonical section 7 is angularly related to a section 8 preferably Iforming a part-ofthe surface of a sphere, said section 8 .merging into a conical section L,9, I.preferably .rounded .at its apex.

The portion of the above described diaphragm Dl Within the corrugated section 6 may aptly be designated as the-plunger portion and,.infaccordance with my invention, it is highly ,desirable that said plunger portion, on one or both faces, be provided with minor indentations, .the latter, as was the case with the diaphragm lillustrated in Figs. l and 2, contributing .to l.a -mankedextent to the yacoustic efficiency of vthe diaphragm.

A 1diaphragm of the character lillustrated in fFigs. l and 2, as Well ,understood in .the art, .may :be connected .by a spider or the like, not shown, to some vibrating member, for example, a machine .or phonograph needle,or the armature ofa loud speaker. lith vsuch a construction, ,the driving connection for .the diaphragm is .distributed .over a substantial .area Aof one face thereof.

On the .other hand with a .diaphragm construction suc'h as illustrated in Figs. 3 and it, the ,diaphragm is Adriven or operated by a member Yconnected thereto `only at its center, such, for example, as illustrated in Fig. Where the diaphragm D1 has a member l0 soldered or otherwise suitably secured there- L to only .at its mid-point, said member l0 terminating in a stylus bar 11 which comprises the usual threaded member l2 for maintaining a phonograph needle, not shown, in assembled relation therewith. Y

As stated above, thev member or material from which the diaphragm is to be formed may be provided with the hereindescribed minorcorrugationsat any suitable time either before, While, or after .the member is brought to diaphragm-forming configuration. Preferably, however, when the diaphragm is formed by a die shaping operation, the minor oorrugations are formed `on one or both faces thereof during the last stage shaping operatien.. Y

For Asuch last Vstage operation there may be utilized a die structure of the character illustrated -in Fig. 7, said die structure comprising arfemale die F and a cooperating male die M, said dies being shaped to bring the diaphragm to suitable configuration such, for example, as illustrated in Fig. 4. Disposed between one of the faces of the diaphragm D1 and one of the dies, for example, the female die F is a sheet R of yielding material such, for example, as soft rubber. lVith this arrangement, there is disposed between the other vface of diaphragm D1 and the male die M a member or sheet of material S suitable for forming the aforesaid minor corrugations in the diaphragm D1. The member S may be any one of a number of suitable materials, for example, finely meshed Wire screen, cloth, muslin or burlap.

It is desirable that diaphragms utilizable as herein described be formed from suitable sheet material such, for example, as an aluminum alloy of the type known to the ltrade as 3 S. O. having a thickness yof the Iorder -of 0.002 of an inch, more or less. Material of this character may be readily deformed or shaped and is inherently Icapable of retaining a set formation. Accordingly, upon relative movement of the dies M and F toward each other, the diaphragm D1 receives not only the configuration imposed by said dies but is provided with minor indentations due to the presence of the sheet fabric S. rlhe provision of a rubber sheet R, when the diaphragm is of suitable thinness, permits slight bodily movement of adjacent small portions of the diaphragm so that the aforesaid minor indentations appear on both sides of the diaphragm, a depression on one side being opposite a raised portion on the other side, Fig. 6. Obviouslyin lieu of the constructions illustrated, the rubber sheet R may be omitted and sheets of fabric or the like, disposed on opposite sides of the diaphragm, each sheet .of fabric, then, functioning as a corrugating member.

Essentially, my invention involves the provision, on one or both faces of the diaphragm, of the above described minor indentations over any desired area thereof but preferably "if only Within the aforesaid tangential corrugations and arranged, preferably, in regular or symmetrical order. The minor corrugations on one face of the diaphragm may vary greatly in number, and ordinarily are of such small dimensions that the contour of the diaphragm is only slightly altered. Thus, for example, inwardly of the above described plunger portion there may be provided substantially 50 corrugations per square inch, more or less, although usually it is desirable that their number be much greater, such, for example, as 600 per square inch, or more. lVhen thus corrugated, the diaphragm is mechanically strengthened and, as a result, its acoustic properties are improved. In this sense, it has been shown, by experience and tests, that an increase is eected in the volume of the sound reproduction While at the same time, any undue tendency of the diaphragm,

in different regions thereof, to respond to particular frequencies is decreased or suppressed.

I claim as my invention:

1. A diaphragm comprising a peripheral section, and a plurality of sections angularly disposed with respect to said peripheral section, said second named sections being provided with a plurality of minor indentations and projections, said indentations and projections being of relatively small dimensions so that the contour of said sections is substantially unaltered.

2. A diaphragm comprising a section of an aluminum alloy having a thickness of the order of 0.002 of an inch and having an indented surface, the indentations in said surface being of relatively small dimensions so that the contour of said diaphragm section is substantially unaltered.

3. A diaphragm comprising a section of an aluminum alloy having a thickness of the order of 0.002 of an inch and having an indented surface, the indentations in said surface numerically exceeding one hundred per square inch.

4. Ardiaphragm comprising a corrugated peripheral portion, and a central plunger portion having a plurality of concentric annular portions of predetermined configuration, said annular portions having minor indentations and projections formed on their surfaces Without substantial deformation of said annular portions from their predetermined conliguration.

5. A diaphragm of thin sheet metal having a plurality of concentric annular portions of conical configuration, said portions having minor surface indentations and projections formed on their surfaces Without substantial deformation of said annular portions.

6. A diaphragm of thin sheet metal having a plurality of concentric annular portions of conical configuration, said portions being provided With minor surface indentations numerically exceeding one hundred per square inch Without deforming said annular portions.

In testimony whereof I have signed this specification this 12thv day of .I une, 1928.

WILBUR L. TYRRELL. 

